JP2002278143A - Full-color, image forming method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method and a device for image formation which solve problems of transfer absence, a dust image due to toner, etc., caused during contact transfer by a full-color image formation system using an intermediate transfer system and obtain well-color-balanced high picture quality, and to provide stable images not only in the beginning, but also thereafter. SOLUTION: For color development, (a) the toner contains three kinds of additives, i.e., (1) silica of 0.01 to 0.03 μm in primary particle size after hydrophobic processing, (2) titanium oxide of 0.01 to 0.03 μm in primary particle size and 60 to 140 m<2> /g in specific surface area after hydrophobic processing, and (3) of 30 to 150 m<2> /g in specific surface area and 100 to 250 g/l in bulk density after hydrophobic processing. (b) When toner in early processing order of cyan and magenta is denoted as A and toner in later processing order is denoted as B, the additive (1) is added to A more than to B, (c) the absolute value |QA/m| of the toner electrostatic charging quantity at this time is larger than |QB/m|, and (d) secondary transfer is carried out while a transfer device applied with a transfer bias is made to abut to >=3 g/cm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a full-color image forming method and apparatus using an electrophotographic system, such as a printer and a copying machine, and a color toner used in the method.
More specifically, primary transfer for transferring a toner image from an image bearing member to an intermediate transfer member through an intermediate transfer member such as an intermediate transfer belt, and secondary transfer for transferring a primary transfer image on the intermediate transfer member to a transfer material. The present invention relates to an image forming method and apparatus for forming an image after each transfer process, and a color toner for developing an electrostatic image used in the image forming method and apparatus.

[0002]

2. Description of the Related Art Conventionally, in a color image forming apparatus such as a color printer or a copying machine for forming a color image by using an electrophotographic recording system, an electrostatic latent image is formed on an image carrier for each, and this is formed. A full-color toner image is formed by developing with a color toner of each color and electrostatically transferring the toner image on the image carrier to a transfer member. Then, for example, the 1 formed on the image forming carrier is
The toner images of the second, third, and fourth colors are sequentially superimposed and transferred (primary transfer) onto an intermediate transfer member, and a color toner image is formed on the intermediate transfer medium. An intermediary transfer system is provided in which transfer is performed collectively (secondary transfer).

In the case of this intermediate transfer method, it is easy to take measures and control to prevent color shift, and it is easy to shorten the transfer portion of the transfer member and simplify the transfer path. Relatively many are adopted.

However, in a color image forming apparatus using an intermediate transfer member, a pressing force is applied to the electrostatic latent image on the developing carrier when developing another color, and the transfer process is further increased. A portion having a strong adhesive force is formed between the toner of the electrostatic latent image and the developing carrier, so that it is difficult to transfer the image, and there is a problem that the image is damaged (so-called missing transfer). In addition, even if the transfer is not lost, uneven transfer efficiency occurs, so that the solid image becomes uneven. In particular, a full-color image becomes a very unsightly blurred image (referred to as “transfer unevenness”).

Further, in recent years, full-color printers have become widespread, and image reproducibility has become increasingly important. In printers, there are many recording media having irregularities on the surface, such as recycled paper and bond paper, and irregular-sized paper. Since it is used, there is a problem that the image must be transferred without causing image defects.

Conventionally, in order to solve these problems, measures have been taken to add a large amount of an external additive such as silica as an external additive to reduce the cohesive force of the toner and to prevent transfer omission and transfer unevenness. However, when the amount of the external additive such as silica is increased, the fluidity is improved to some extent with the added amount, but there is a limit. In addition, the amount of suspended particles of silica increases.For example, when an intermediate transfer medium of a urethane-based belt is used, silica released from the toner matrix is driven into the belt to cause scratches, or the silica adheres to the belt. Silica filming occurs.

[0007] Further, the silica becomes a nucleus and is driven into the developing carrier by the pressing force of the cleaning blade to cause scratches.
Then, filming in which silica or toner adheres to the developing carrier occurs. In addition, the suspended matter of silica adheres to the solid image area and white spots are generated.

Further, in the color image forming method of performing the superimposed transfer, there is a problem that the so-called transfer dust, in which the toner is scattered due to an increase in the amount of the additive, causes a reduction in resolution and a deterioration in image quality.

As a method for solving these problems, Japanese Patent Application Laid-Open Nos. Hei 7-181732 and Hei 7-181733 disclose a method of transferring toner by making a toner used in an intermediate transfer type image forming apparatus into a spherical shape. It is described that transfer omission (transfer unevenness) and scattering are improved. However, although there was a slight improvement effect on transfer omission, the effect was still insufficient, and there was almost no effect on transfer dust. In particular, in the case of one-component development, when the shape is made spherical, there is a problem that the frictional charging with the blade becomes insufficient and the charging of the toner becomes unstable.

[0010] In the intermediate transfer system, these transfer omissions (transfer irregularities) are more likely to occur in a color in an earlier development order. That is, the image formed on the image forming carrier,
For example, the toner images of the first color, the second color, the third color, and the fourth color are transferred to the intermediate transfer member, and the first, second, third, and fourth toner images are transferred.
In the case where the toner layers of the first layer are formed by overlapping, the first color toner on the intermediate transfer member overlaps the second and subsequent colors, regardless of whether or not the second color overlaps.
If it is the second color, it will pass through three times. For this reason, when a transfer pressure is applied in the primary transfer step other than during image formation, the earlier the development order, the stronger the cohesive force in the transfer toner layer, and the less the transfer from the toner layer closest to the intermediate transfer member. It is considered to be for the purpose.

On the other hand, with regard to transfer dust, when the fluidity is high and the cohesive force between the toners is relatively small, the toner can easily move even with a slight repulsive force between the toners. In addition, a repelling force due to the same polarity of the toner may act between the already-transferred toner and the next-transferred toner, so that the toner is easily scattered.

In order to solve this problem, Japanese Patent Publication No. 26800
No. 81 describes that by setting the order of superimposed transfer by toner in the order of increasing content of the fluidity improving additive, transfer dust and prevention of transfer omission can be solved. Is insufficient, especially in a developing method in which a contact pressure of a transfer roller or the like is applied, and transfer dust has not been solved.

It is also conceivable to lower the charge amount in order to reduce the transfer dust, but if the charge amount of the toner is low and the amount of toner of the opposite polarity increases, the toner adheres to the background and the output on the transfer paper is reduced. In the image, there is a defect that appears as a fog on the background. In particular, in a full-color development system in which four colors are developed, the fog at the background becomes quadruple, so that it is easily noticeable. Further, when the rise of the toner charge is poor, there is a problem that the density stability is deteriorated such that a difference in image density occurs between the front and rear ends of the paper or a ghost appears.

[0014] From these facts, regarding the transfer dust,
Full color yellow, cyan,
Reproduce in magenta, black is reproduced only in black,
Means have been taken to reduce the number of superimposed transfers and to set the amount of color superimposition to be reduced by performing inking, but this is not yet sufficient. In addition, when a full color is created with four colors of yellow, magenta, cyan, and black, the color, black, magenta, cyan,
Yellow is more noticeable in the order, but black is less likely to be overlaid, so when one or both of magenta and cyan are overlaid, the transfer dust becomes very noticeable. Target transfer dust is hardly noticeable, and does not greatly affect image reproducibility.

On the other hand, conventionally, electrophotographic processes using a one-component developer are classified into a magnetic one-component developing system using a magnetic toner and a non-magnetic one-component developing system using a non-magnetic toner. The magnetic one-component developing method uses a developer carrier provided with a magnetic field generating means such as a magnet inside, holds a magnetic toner containing a magnetic substance such as magnetite, and develops a thin layer by a layer thickness regulating member. In recent years, a large number of printers have been put to practical use. On the other hand, in the non-magnetic one-component developing method, since the toner does not have a magnetic force, a toner supply roller is pressed against the developer carrier to supply the toner onto the developer carrier and electrostatically hold the toner. The layer thickness regulating member is used to develop a thin layer, which has the advantage of being compatible with colorization because it does not contain a colored magnetic material, and has a lighter weight because no magnet is used for the developer carrier. In recent years, it has become possible to reduce costs and reduce the cost.

However, there are still many problems to be improved in the one-component developing system. In the one-component developing method, since there is no stable charging and conveying means unlike the carrier used in the two-component developing method, charging and conveying failure due to high speed are likely to occur. That is, in the one-component developing method, after the toner is conveyed onto the developer carrying member, the toner is thinned and developed by the layer thickness regulating member, but the toner and the developer carrying member, the layer thickness regulating member and the like are charged by friction. Since the contact and frictional charging time with the member is very short, the amount of low-charge and reverse-charge toner tends to increase more than in the two-component developing method using a carrier. At present, in order to improve these, in the one-component developing system, the toner is forcibly charged by applying pressure to a regulating member, a supply roller and the like. However, even if a good image is initially obtained, the load on the toner is increased, so that the toner is particularly deteriorated with the passage of time. Happened
This has been a problem in terms of long-term stability.

As a solution to these problems, Japanese Patent Application Laid-Open No. 5-533
69, an inorganic fine powder having a BET specific surface area of 1 to 150 m ² / g and treated with a coupling agent having a saturated or unsaturated cyclic or acyclic organic group having 5 or more carbon atoms;
A toner having an inorganic fine powder having a T specific surface area of 160 to 400 m ² / g and a hydrophobicity of 30 or more is disclosed. However, the charging characteristics of the toner on the developing sleeve become unstable, and the toner spills from the developing sleeve. May be scattered.

Further, Japanese Patent Application Laid-Open No. 6-202374 discloses a non-magnetic one-component toner in which inorganic fine particles having an average particle diameter of 30 nm or more and less than 100 nm are adhered. May become insufficiently replenishable.

Further, JP-A-8-15890 discloses toner particles having an average particle size of 4 to 9 μm and a small particle size (7 to 20 nm).
And a one-component developer comprising an external additive having a large particle diameter (20 to 80 nm) and having a small particle diameter of 1 to 2% by weight, but the charging characteristic of the toner on the developing sleeve is unstable. This may cause the toner to spill or scatter from the developing sleeve.

JP-A-9-288369 discloses a BET specific surface area of 20 to 50 m ² / g, a pH of 6 to 8, and a hydrophobicity of 85%.
Although the toner containing the above silica fine particles is disclosed, the fluidity of the toner is not sufficient, and the toner replenishing property may be insufficient.

[0021]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a full-color image forming method using an intermediate transfer system, which solves the above-mentioned problems such as transfer omission occurring at the time of contact transfer and dust images due to toner. An object of the present invention is to provide an image forming method and an image forming apparatus capable of obtaining balanced high image quality.

It is a further object of the present invention to provide a stable image not only at the initial stage but also with the lapse of time in a non-magnetic one-component developing system.

A further object of the present invention is to solve the above-mentioned problems such as transfer omission and toner dust caused by toner during contact transfer not only at the initial stage but also with time in an image forming method using an intermediate transfer system. An object of the present invention is to provide a color toner for developing an electrostatic charge image.

[0024]

As a result of intensive studies conducted by the present inventor, it has been found that in order to be able to output stable image quality characteristics over time without transfer omission or transfer dust, yellow,
It has a developing unit for four colors of cyan, magenta and black, each of which forms an electrostatic latent image on an image carrier, develops it with each toner, and intermediately transfers the toner image on the image carrier. After the step of primary transfer to the transfer member, the toner image on the intermediate transfer member is secondarily transferred collectively to a transfer member, and when the toner on the transfer member is fixed, full-color reproduction is performed in yellow, cyan, and magenta. In an image forming method in which only three colors are superimposed and only black is used in a single color,

A. The full-color toner is a toner containing at least a binder resin and a colorant, and further containing at least the following three types of external additives, and a silica having a primary particle diameter of 0.01 to 0.03 μm and subjected to hydrophobic treatment. Primary particle size 0.01 to 0.03 μm and specific surface area 60 to
140 m ² / g hydrophobized titanium oxide Specific surface area 30 to 150 m ² / g, bulk density 100 to 25
0 g / l hydrophobized silica b. ) Assuming that the toner in the earlier development order of cyan and magenta is A and the toner in the later development order is B, the added amount of the external additives is A> B, c. ) At this time, the absolute value of the toner charge amount | Q _A / m |
| Q _B / m | is | Q _A / m |> | Q _B / m | d. The secondary transfer is performed by bringing a transfer device to which a transfer bias is applied into contact with the transfer device at 3 g / cm or more to transfer a toner image to a transfer member, and / or the above-described a. B). ) C. When the toner satisfies the condition (1), the above problem can be achieved.

According to the present invention, there are four color developing units of yellow, cyan, magenta, and black. For each, an electrostatic latent image is formed on an image carrier, and this is developed with each toner. After the step of primary transferring the toner image on the image carrier to the intermediate transfer member is performed, the toner image on the intermediate transfer member is secondarily transferred collectively to the transfer member, and the toner on the transfer member is fixed. In the full-color image forming method, a. The full-color toner is a toner containing at least a binder resin and a colorant, and further containing at least the following three types of external additives, and a silica having a primary particle diameter of 0.01 to 0.03 μm and subjected to hydrophobic treatment. Primary particle size 0.01 to 0.03 μm and specific surface area 60 to
140 m ² / g hydrophobized titanium oxide Specific surface area 30 to 150 m ² / g, bulk density 100 to 25
0 g / l hydrophobized silica b. ) When the toner having the earliest development order among cyan, magenta and black is A, the toner having the second development order is B, and the toner having the latest development order is C, the addition amount of the external additives is A> B > C, c. ) At this time, the absolute value of the toner charge amount | Q _A / m |
_{| Q B / m |, |} Q C / m | is _{| Q A / m |> |} Q B / m |
> | Q _C / m | d. 2.) The secondary transfer is a method in which a transfer device to which a transfer bias is applied is brought into contact with the transfer device at 3 g / cm or more to transfer a toner image to a transfer member. The above a. B). ) C. When the toner satisfies the condition (1), the above problem can be achieved.

Further, according to the present invention, there are four color developing units of yellow, cyan, magenta and black, each of which forms an electrostatic latent image on an image carrier and develops the latent image with each toner. After the step of primary transferring the toner image on the image carrier to the intermediate transfer member, the toner image on the intermediate transfer member is collectively secondarily transferred to a transfer member, and the toner on the transfer member is fixed. In a full-color image forming method, a. The full-color toner is a toner containing at least a binder resin and a colorant, and further containing at least the following three types of external additives, and a silica having a primary particle diameter of 0.01 to 0.03 μm and subjected to hydrophobic treatment. Primary particle size 0.01 to 0.03 μm and specific surface area 60 to
140 m ² / g hydrophobized titanium oxide Specific surface area 30 to 150 m ² / g, bulk density 100 to 25
0 g / l hydrophobized silica b. When the toner having the earliest development order among yellow, cyan, magenta, and black is A, the second toner is B, the third toner is C, and the toner having the latest development order is D, The addition amount of which is A>B>C> D, c. ) At this time, the absolute value of the toner charge amount | Q _A / m |
| Q _B / m |, | Q _C / m |, | Q _D / m | is | Q _A / m |
_{> | Q B / m |>} | Q C / m |> | Q D / m | d. The secondary transfer is performed by bringing a transfer device to which a transfer bias is applied into contact with the transfer device at 3 g / cm or more to transfer a toner image to a transfer member, and / or the above-described a. B). ) C. It is more preferable that the toner satisfies (1).

Further, according to the present invention, when the developing section is of a non-magnetic one-component developing type, it is very preferable because a stable image can be provided without deterioration of the toner even with the passage of time.

In the generation of a full-color image, it is difficult to uniformly transfer the toner images of four colors. Further, when an intermediate transfer member is used, problems are likely to occur in terms of color unevenness and color balance. Is not easy to output stably over time.

For this reason, the present inventors use at least three kinds of additives as external additives of each color toner in the intermediate transfer and the contact transfer, and adjust and optimize the amount of the additives and the toner charge amount in the order of development. This has led to the solution of the present invention.

That is, when a full-color image is reproduced by color superimposition, if the amount of the external additive is increased in the earlier development order, coagulation due to the transfer pressure and other stresses occurs in the primary transfer. Becomes difficult,
Furthermore, in the case of layering on the intermediate transfer member, the layer closest to the intermediate transfer member (that is, the layer farthest from the transfer material in the case of the secondary transfer)
Are less likely to agglomerate, so that in secondary transfer in which a transfer pressure and a transfer bias are applied, the releasability from the intermediate transfer member is excellent, and transfer loss (transfer blur) is less likely to occur.

Further, regarding charging, the absolute amount of charge is adjusted to be higher in the order of development in forming a superimposed image, so that electrostatic repulsion between toners is reduced. From what develops from the low charge,
Since static repulsion is less likely to occur than when the charge does not change or the charge is high, transfer dust can be reduced.

Further, since the total amount of the external additives can be reduced, it is also effective in preventing white spots caused by silica such as silica filming.

In this case, since yellow is a light color, it is hardly noticeable in the actual image even if transfer dust or the like actually occurs. It is better to match it. But you don't have to be caught.

For this reason, when full color is reproduced by superimposing three colors of yellow, cyan and magenta except for black,
In the case where the relationship between magenta and cyan is to reproduce full color by superimposing four colors, the magenta, cyan, and black toners are preferably externally added in the order that the yellow, magenta, cyan, and black toners are developed earlier. It is necessary that the larger the amount of the agent and the earlier the order of development, the higher the absolute value of the charge amount.

FIG. 1 shows an example of a full-color image recording method applicable to the present invention.

In these apparatuses, an electrostatic latent image is formed on the photoreceptor (2) by a writing optical unit (not shown) for optically writing image data corresponding to a document image. The optical unit is known per se, and includes a laser diode, a polygon mirror, a polygon motor, an imaging lens, a reflection mirror, and the like. The photoreceptor (2) rotates counterclockwise as indicated by an arrow, and although not shown, a cleaning unit including a pre-cleaning neutralizer, a cleaning roller and a cleaning blade, a neutralizing lamp, A charger, a development pattern detector, and the like are provided. Then, in order to develop the electrostatic latent image, each of the developing devices (1a to 1d) supplies the developer to a developing sleeve that rotates so as to face the photoconductor. Here, the order of the developing operation (color toner forming order) is C,
The operation will be described below with an example of M, Y, and Bk (however,
The order is not limited to this).

When the printing operation is started, light writing of the C image data by laser light and formation of a latent image are started at a predetermined timing (hereinafter, referred to as a C latent image. The same applies to M, Y, and Bk). . In order to enable development from the leading end of the C latent image, the developing sleeve is started to rotate before the leading end of the latent image reaches the developing position of the C developing device (1a) to convert the C latent image into the C toner (charging amount). Development). Thereafter, the developing operation of the C latent image area is continued, but when the rear end of the C latent image passes the C developing position, the developing operation is stopped. This is completed at least before the next M image front end reaches.

Next, the C toner image formed on the photoconductor (2) is transferred to the surface of the intermediate transfer member (3) (hereinafter, the toner image is transferred from the photoconductor (2) to the intermediate transfer member (3)). Is referred to as “primary transfer”). The primary transfer is performed by applying a transfer bias voltage in a state where the photosensitive member (2) and the intermediate transfer member (3) are in contact with each other. Then, C, M, Y, B sequentially formed on the photoconductor (2) are formed on the intermediate transfer body (3).
The k toner images are sequentially aligned on the same surface to form a four-color superimposed primary transfer image, and then collective transfer (secondary transfer) to transfer paper is performed. The unit configuration and operation of the intermediate transfer member (3) will be described later.

On the photoconductor (2) side, after the C step, the process proceeds to the M step using the M toner in which the amount of addition of the external additive and the charge amount are controlled as described above. An M latent image is formed by laser light writing.
The M developing unit (1b) starts rotating the developing sleeve with respect to the developing position after the trailing end of the preceding C latent image has passed and before the leading end of the M latent image has arrived. Develop. Thereafter, the development of the M latent image area is continued, but when the rear end of the latent image has passed, the development is made inoperative as in the case of the C developing device. This is also completed before the leading end of the next Y latent image arrives. The operations of Y and Bk are the same as those of the above-described steps C and M, except that the toner of each color is used. In the primary transfer, a transfer pressure is applied during image formation as described above. In particular, if the image formation order is the first color, the transfer pressure including the image formation of itself is applied four times, so that the transfer pressure in the toner layer is increased. It is preferable to reduce the pressure even a little because the cohesive force becomes strong, but by using the photoreceptor as a photoreceptor belt at this time, local pressure can be released during the primary transfer. For this reason, it is preferable to use a photosensitive belt.

The intermediate transfer member (3) is bridged by a transfer bias roller, a drive roller, a driven roller, and the like, and is driven and controlled by a drive motor. In addition, a cleaning unit or the like may be provided around the intermediate transfer member as necessary, and in this case, a contact / separation operation is performed by a contact / separation mechanism. The timing of the contact / separation operation is set to be separated from the surface of the intermediate transfer member (3) from the start of printing until the end of the primary transfer of Bk (the fourth color of the last color in this example). Cleaning is performed by contacting the surface of the intermediate transfer member (3) with a separation mechanism.

For the intermediate transfer member, it is preferable to use a belt system because a local pressure can be released, and a combination of a photosensitive belt and an intermediate transfer belt is most preferable (FIG. 2). In addition, by applying a small amount of zinc stearate to the surface of the intermediate transfer member, the surface energy of the intermediate transfer member is reduced, and the releasability from the toner layer is further improved. It is desirable because the cleaning property can be improved.

The secondary transfer to the transfer paper or the like is constituted by a transfer bias roller (4) (electric field forming means for secondary transfer) and a mechanism (not shown) for contacting / separating from the intermediate transfer body (3). Have been. The bias roller (4) is normally separated from the intermediate transfer member (3), but is used to transfer a four-color superimposed image formed on the surface of the intermediate transfer member (3) onto the transfer material (6). The roller is pressed at a rate of 3 g / cm or more by a contact / separation mechanism at a predetermined timing, and a predetermined bias voltage is applied to the roller (4) to perform transfer to the transfer paper (6). If the pressing force is less than 3 g / cm, the transfer material is likely to be displaced during the secondary transfer and the transfer material is likely to be displaced, so that normal printing on the transfer material cannot be performed.

Further, as shown in FIG.
The transfer material (6) on which the color superimposed images are collectively transferred is conveyed on paper and conveyed to a fixing device (5), and the toner image is fused and fixed by a fixing roller and a fixing belt and a pressure roller controlled to a predetermined temperature. The obtained full color print can be obtained.

The toners used in the present invention are four color toners of yellow, cyan, magenta and black.

Examples of the binder resin used in the present invention include polymers of styrene such as polystyrene, poly p-chlorostyrene, and polyvinyl toluene, and their substituted polymers; styrene-p-chlorostyrene copolymer, and styrene-propylene copolymer. Styrene-vinyltoluene copolymer, styrene-vinylnaphthalene copolymer, styrene-methyl acrylate copolymer, styrene-ethyl acrylate copolymer, styrene-butyl acrylate copolymer, styrene-
Octyl acrylate copolymer, styrene-methyl methacrylate copolymer, styrene-ethyl methacrylate copolymer, styrene-butyl methacrylate copolymer, styrene-α-chloromethyl methacrylate copolymer, styrene-
Acrylonitrile copolymer, styrene-vinyl methyl ketone copolymer, styrene-butadiene copolymer, styrene-isoprene copolymer, styrene-acrylonitrile-indene copolymer, styrene-maleic acid copolymer,
Styrene-based copolymers such as styrene-maleic acid ester copolymers; polymethyl methacrylate, polybutyl methacrylate, polyvinyl chloride, polyvinyl acetate, polyethylene, polypropylene, polyester, epoxy resin, epoxy polyol resin, polyurethane, polyamide, polyvinyl Butyral, polyacrylic acid resin, rosin, modified rosin, terpene resin, aliphatic or alicyclic hydrocarbon resin, aromatic petroleum resin, chlorinated paraffin, paraffin wax, etc. can be used alone or in combination.

Further, in a full-color image, since several types of toner layers are superposed one on another, the toner layer becomes thicker, causing cracks or defects in the image due to insufficient strength of the toner layer, or losing appropriate gloss. Or For this reason, a polyester resin or a polyol resin is particularly preferable in order to maintain appropriate gloss and excellent strength.

The polyester resin can be generally obtained by an esterification reaction between a polyhydric alcohol and a polycarboxylic acid. Among the monomers constituting the polyester resin in the present invention, examples of the alcohol monomer including tri- or higher-valent polyfunctional monomers include, for example, ethylene glycol, diethylene glycol triethylene glycol, 1,2-propylene glycol, and 1,3-propylene glycol. Glycols, 1,4-butadieneol, neopentyl glycol, 1,4-butenediol, 1,5-pentanediol, diols such as 1,6-hexanediol, bisphenol A, hydrogenated bisphenol A, polyoxypropylene Bisphenol A alkylene oxide adducts such as bisphenol A, other dihydric alcohols, or sorbitol, 1,2,3,6-hexanetetrol, 1,4-sorbitan, pentaerythritol, dipentaerythritol Le, tripentaerythritol, 1,2,4-butanetriol, 1, 2, 5
-Pentanetriol, glycerol, diglycerol, 2-methylpropanetriol, 2-methyl-1,
Examples thereof include 2,4-butanetriol, trimethylolethane, trimethylolpropane, 1,3,5-trihydroxybenzene, and other trihydric or higher polyhydric alcohols.

Among these monomers, those using a bisphenol A alkylene oxide adduct as a main component monomer are particularly preferably used.

When a bisphenol A alkylene oxide adduct is used as a constituent monomer, a polyester having a relatively high glass transition point is obtained due to the nature of the bisphenol A skeleton, and the anti-copy blocking property and heat storage stability are improved. In addition, the presence of the alkyl groups on both sides of the bisphenol A skeleton functions as a soft segment in the polymer, and improves color developability and image strength during toner fixing. In particular, among the bisphenol A alkylene oxide adducts, those having an ethylene group or a propylene group are preferably used.

Among the monomers constituting the polyester resin in the present invention, examples of the acid monomer, including trifunctional or higher polyfunctional monomers, include, for example, maleic acid, fumaric acid, citraconic acid, itaconic acid, glutaconic acid and phthalic acid. , Isophthalic acid, terephthalic acid, cyclohexanedicarboxylic acid, succinic acid, adipic acid, sebacic acid, azelaic acid, malonic acid, or n-dodecenylsuccinic acid,
Alkenyl succinic acids or alkyl succinic acids such as n-dodecyl succinic acid, anhydrides of these acids, alkyl esters, other divalent carboxylic acids, and 1,
2,4-benzenetricarboxylic acid, 2,5,7-naphthalenetricarboxylic acid, 1,2,4-naphthalenetricarboxylic acid, 1,2,4-naphthalenetricarboxylic acid,
2,4-butanetricarboxylic acid, 1,2,5-hexanetricarboxylic acid, 1,3-dicarboxyl-2-methyl-methylenecarboxypropane, tetra (methylenecarboxyl) methane, 1,2,7,8-octanetetra Carboxylic acids, empole trimer acids and their anhydrides,
Examples thereof include alkyl esters, alkenyl esters, aryl esters, and other trivalent or higher carboxylic acids.

As specific examples of the alkyl group, alkenyl group or aryl ester described herein, 1,2,2
4-benzenetricarboxylic acid, 1,2,4-benzenetricarboxylic acid trimethyl, 1,2,4-benzenetricarboxylic acid triethyl, 1,2,4-benzenetricarboxylic acid tri-n-butyl, 1,2,4-benzenetricarboxylic acid Isobutyl, tri-n-octyl 1,2,4-benzenetricarboxylate, tri-2-ethylhexyl 1,2,4-benzenetricarboxylate, tribenzyl 1,2,4-benzenetricarboxylate, 1,2,4-benzenetricarboxylate Acid tris (4-isopropylbenzyl);

It is known that the relationship between the chargeability of a polyester resin and the acid value is almost proportional to each other. It is known that the higher the acid value, the greater the negative chargeability of the resin. Also affect. That is, when the acid value is high, the charge amount becomes high under low temperature and low humidity, and the charge amount becomes low under high temperature and high humidity, the background stain, the image density, the change in color reproducibility become large, and it is difficult to maintain high image quality. . Therefore, the acid value of the polyester resin is preferably 20 KOH mg / g or less, and more preferably 5 KOH mg / g or less.

As the polyol resin, from the viewpoints of environmental stability of charging, fixing stability, color reproducibility, gloss stability, curling prevention after fixing, etc., the end of the epoxy resin is capped, and the main chain is made of poly. Those having an oxyalkylene moiety are preferred. For example, it can be obtained by reacting an epoxy resin having glycidyl groups at both terminals and an alkylene oxide adduct of dihydric phenol having glycidyl groups at both terminals with dihalide, isocyanate, diamine, diol, polyhydric phenol, or dicarboxylic acid. Of these, the reaction with a dihydric phenol is most preferable in terms of reaction stability. It is also preferable to use a polyhydric phenol or a polycarboxylic acid together with a dihydric phenol within a range not causing gelation.

The following are examples of the alkylene oxide adduct of a dihydric phenol having a glycidyl group at both terminals used in the present invention. Examples include ethylene oxide, propylene oxide, butylene oxide, and reaction products of these mixtures with bisphenols such as bisphenol A and bisphenol F. The obtained adduct may be used after glycidylation with epichlorohydrin or β-methylepichlorohydrin. In particular, the following general formula (1)
Glycidyl ether of an alkylene oxide adduct of bisphenol A represented by

[0056]

Embedded image

As the coloring agent, all known dyes and pigments can be used. Examples of yellow include naphthol yellow S, Hansa yellow (10G, 5G, G), cadmium yellow, yellow iron oxide, yellow clay, yellow Lead, titanium yellow, oil yellow, Hansa yellow, (GR, A, R
N, R), Pigment Yellow L, Benzidine Yellow (G, GR), Permanent Yellow (NCG), Vulcan Fast Yellow (5G, R), Tartrazine Lake, Quinoline Yellow Lake, Anslagen Yellow B
GL, isoindolinone yellow,

Examples of magenta toners include Risor Fast Scarlet G, Brilliant Fast Scarlet, Brilliant Carmine BS, Permanent Red (E2R, F4R, FRL, FRLL, F4RH),
Fast Scarlet VD, Belkan Fast Rubin B, Brilliant Scarlet G, Lisor Rubin G
X, permanent red F5R, brilliant carmine 6B, pigment scarlet 3B, bordeaux 5B, toluidine marine, permanent bordeaux F2K, helio bordeaux BL, bordeaux 10B, bon marine light, bon marine medium, eosin lake, rhodamine rake B, rhodamine rake Y , Alizarin rake,
Thioindigo red B, thioindigo maroon, oil red, quinacridone red, pyrazolone red, chrome vermillion, benzidine orange, perinone orange, oil orange,

Examples of the cyan toner include cobalt blue, cerulean blue, alkali blue lake, peacock blue lake, Victoria blue lake, metal-free phthalocyanine blue, phthalocyanine blue, fast sky blue, and indanthrene blue (RS, B
C), indigo, ultramarine, navy blue, anthraquinone blue,
Fast Violet B, Methyl Violet Lake,
Cobalt purple, manganese purple, dioxazine violet,
Anthraquinone violet, chrome green, zinc green, chromium oxide, pyridian emerald green, pigment green B, naphthol green B, green gold, acid green lake, malachite green lake, phthalocyanine green, anthraquinone green, titanium oxide, zinc oxide, lithbon, and Their mixture,

Examples of the black toner include carbon black, nigrosine dye, iron black, and a cyan-based pigment as a complementary color. The amount used is generally 0.1 to 50 parts by weight with respect to 100 parts by weight of the binder resin for each color.

The yellow, cyan, magenta, and black toners of the present invention have an external additive. The following three types of external additives are used in the present invention. (I) Hydrophobized silica having a primary particle diameter of 0.01 to 0.03 μm (II) Specific surface area of 6 having a primary particle diameter of 0.01 to 0.03 μm
0 to 140 m ² / g hydrophobically treated titanium oxide (III) specific surface area 20 to 50 m ² / g, bulk density 100 to 2
50 g / l of hydrophobized silica.

By attaching the hydrophobically treated silica (I) having a primary particle size of 0.01 to 0.03 μm to the surface of the toner, necessary fluidity and chargeability are imparted to the toner,
The developability of the photosensitive member on the developing sleeve and from the developing sleeve is improved. The addition amount of this type of silica is preferably 0.1 to 1.5 parts by weight based on 100 parts by weight of the base toner. If the amount is less than this, the necessary amount of toner is supplied to the developing sleeve. Or the required amount of toner charge may not be obtained. Further, when the amount is larger than the above range, the chargeability of the toner may be too high to sufficiently develop the toner or the toner may be scattered from the developing sleeve. In addition, by adjusting the addition amount according to the order of development as described above, it is possible to obtain a good image without transfer dust and uneven transfer.

The primary particle size is 0.01 to 0.03 μm.
The hydrophobicized titanium oxide (II) having a specific surface area of 60 to 140 m ² / g with respect to 100 parts by weight of the base toner,
By attaching the toner to the surface of 0.1 to 1.5 parts by weight of the toner, the chargeability of the toner is stabilized, and in particular, charge-up is prevented. If the added amount of this type of titanium oxide is less than this, the chargeability of the toner is too high to sufficiently develop the toner, or the transfer dust is poor, and the charge-up is caused by the one-component developing method. As a result, the formation of a thin layer cannot be maintained, m / a runs away, and not only the fluctuation of the image density becomes large, but also the toner may spill from the developing roller. If the amount is larger than the above range, the charge amount of the toner may be so low that the toner may be scattered from the developing sleeve or may cause background stain.

Further, a hydrophobically treated silica (II) having a specific surface area of 20 to 50 m ² / g and a bulk density of 100 to 250 g / l
I) was added in an amount of from 0.3 to 2. based on 100 parts by weight of the base toner.
By attaching the toner to the surface of 0 parts by weight of toner, the thin layer of the toner on the developing sleeve becomes uniform, the unevenness of the thin layer is largely improved, and the rotation of the developing sleeve for a long period of time,
The generation of white stripes due to the fusion of the toner to the layer thickness regulating member (blade or roller) is prevented. If the amount of silica of this type is smaller than this, the thin layer of the toner on the developing sleeve becomes non-uniform, and uniform development of the toner and an image cannot be obtained. White streaks may occur due to fusion of toner to blades and rollers). When added in an amount larger than this, the silica of this type is excessively present and may not adhere to the surface of the toner, which may impair the charging stability of the toner.

The two types of silica used in the present invention are generally produced by a wet method or a dry method, and in particular, a so-called fume produced by a dry method (vapor phase oxidation of a siliconated halogen compound). What is called silica is preferable from the viewpoint of fluidity.

The toner of the present invention may contain a charge controlling agent, if necessary. As the charge control agent, any known charge control agent can be used. Quaternary ammonium salts), alkyl amides, phosphorus alone or compounds, tungsten alone or compounds, fluorine-based activators, salicylic acid metal salts, and salicylic acid derivative metal salts.

In the present invention, the amount of the charge control agent used is determined by the type of binder resin, the presence or absence of additives used as required, and the toner production method including the dispersion method, and is uniquely limited. However, it is preferably 0.1 to 1 part by weight based on 100 parts by weight of the binder resin.
It is used in the range of 0 parts by weight. Preferably, the range is 2 to 5 parts by weight. If the amount is less than 0.1 part by weight, the negative charge of the toner is insufficient, which is not practical. If the amount exceeds 10 parts by weight, the chargeability of the toner is too large, and the image density is reduced due to spent or filming due to an increase in electrostatic attraction with the carrier or the developing sleeve. Moreover, you may use together several charge control agents as needed. Further, the addition amount may be changed depending on the development order of each color toner.

As for the amount of charge of the toner, it is necessary to adjust the amount of charge of each toner according to the order of development as described in the claims. For this reason, the amount of the charge control agent may be changed for each color in order to provide a necessary charge amount for each color.

In the case of a two-component developer, the amount of charge may be adjusted by changing the type of carrier, the amount of charge, etc. for each color, or by changing the stirring force of the developer. If this is the case, the charge amount may be adjusted by changing the material, surface roughness, nip pressure, width, and the like of members related to charging (such as the developing roller and the layer regulating member).

A wax may be contained in the produced developer in order to impart releasability to the produced developer. The wax has a melting point of 40 to 120 ° C., preferably 50 to 110 ° C. When the melting point of the wax is too high, the fixability at low temperatures may be insufficient, while when the melting point is too low, the offset resistance and durability may decrease. The melting point of the wax is determined by a differential scanning calorimetry ( DSC). That is, the melting peak value when a few mg of the sample is ripened at a constant heating rate, for example (10 ° C./min), is defined as the melting point.

Examples of the wax that can be used in the present invention include solid paraffin wax, microwax, rice wax, fatty acid amide wax, fatty acid wax, aliphatic monoketones, fatty acid metal salt wax, and fatty acid ester wax. And partially saponified fatty acid ester waxes, silicone varnishes, higher alcohols, and carnauba wax. Polyolefins such as low molecular weight polyethylene and polypropylene can also be used. In particular, a polyolefin having a softening point of 70 to 150 ° C by a ring and ball method is preferable,
Further, a polyolefin having a softening point of 120 to 150 ° C is preferable.

In the present invention, the toner may be used alone as a developer to develop an electrostatic latent image, that is, developed by a so-called one-component developing method, or a two-component developer obtained by mixing a toner and a carrier may be used. The latent image may be developed by a two-component developing method in which the electrostatic latent image is visualized. It can be used more preferably because it hardly deteriorates.

As the carrier used in the two-component developing method, there can be mentioned, for example, iron powder, ferrite, glass beads, and the like. These carriers may be coated with a resin. The resin used in this case is carbon fluoride, polyvinyl chloride, polyvinylidene chloride, phenol resin, polyvinyl acetal, silicone resin and the like. In any case, the mixing ratio of the toner and the carrier is
Generally, 1.5 to 1 toner per 100 parts by weight of carrier
About 0.0 parts by weight is appropriate.

It is particularly preferable to use a one-component developing system. These may be different depending on the developer of each color, but it is necessary that the charge amount of each color toner is finally set to the charge amount as described in the claims.

In producing a plurality of toners of the present invention, the above-mentioned constituent materials are mixed by a mixer such as a Henschel mixer, and then heated and kneaded by a kneader such as a continuous kneader or a roll kneader. After cooling and solidifying the kneaded material,
A method of pulverizing and classifying to obtain a desired average particle size is preferred. Other methods include a spray drying method, a polymerization method and a microcapsule method. Further, the toner thus obtained can be sufficiently mixed with a desired external additive with a mixer such as a Henschel mixer, if necessary, to produce a toner.

[0076]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be specifically described below with reference to examples and comparative examples, but the present invention is not limited to only these examples. In the following examples, parts and percentages are by weight unless otherwise specified.

(Synthesis example of polyester resin) Synthesis example 1 Stirrer, thermometer, nitrogen inlet, falling condenser,
In a four-necked separable flask with a cooling tube, 740 g of polyoxypropylene (2,2) -2,2-bis (4-hydroxyphenyl) propane and polyoxyethylene (2,
2) 300 g of 2,2-bis (4-hydroxyphenyl) propane, 466 g of dimethyl terephthalate, 80 g of isododecenyl succinic anhydride, and 114 g of tri-n-butyl 1,2,4-benzenetricarboxylate were added together with the esterification catalyst. Under a nitrogen atmosphere, the temperature was raised to normal temperature to 210 ° C. in the first half, and the reaction was performed while stirring at 210 ° C. under reduced pressure in the latter half. Acid value 2.3KOHmg / g, hydroxyl value 28.0KOHmg
/ G, a softening point of 106 ° C and a Tg of 62 ° C were obtained (hereinafter referred to as polyester resin A).

(Synthesis Example of Polyol Resin) Synthesis Example 1 378.4 g of a low-molecular bisphenol A type epoxy resin (number average molecular weight: about 360) was placed in a separable flask equipped with a stirrer, a thermometer, a nitrogen inlet, and a condenser. High molecular weight bisphenol A type epoxy resin (number average molecular weight: about 270
0) 86.0 g, glycidylated bisphenol A-type propylene oxide adduct (n + m in the above general formula (1): about 2.1) 191.0 g, bisphenol F
274.5 g, 70.1 g of p-cumylphenol, and 200 g of xylene were added. 70-100 ° C under nitrogen atmosphere
The temperature was raised to 160 ° C., xylene was distilled off under reduced pressure, and
At a reaction temperature of 6 to 9 hours to obtain an acid value of 0.0 KO.
A polyol resin having an Hmg / g, a hydroxyl value of 70.0 KOHmg / g, a softening point of 109 ° C. and a Tg of 58 ° C. was obtained (hereinafter referred to as polyol resin A).

(Production Example of Base Toner) Water 1200 parts Phthalocyanine green water-containing cake (solid content 30%) 200 parts Carbon black (manufactured by Printex 35 Dexa) 540 parts (DBP oil absorption = 42 ml / 100 mg, pH = 9.5) Stir well with a flasher. To this, 1200 parts of polyester resin A was added, kneaded at 150 ° C. for 30 minutes, 1000 parts of xylene was added, kneading was continued for 1 hour, water and xylene were removed, roll-cooled, and pulverized with a pulperizer.
A masterbatch pigment was obtained.

100 parts of polyester resin A 5 parts of the above master batch 5 parts Charge control agent (Orient Chemical: Bontron E-84) 3 parts After mixing the above materials with a mixer, they were melt-kneaded with a two-roll mill, and the kneaded material was rolled and cooled. Thereafter, a jet plate mill (I-2 type mill; manufactured by Nippon Pneumatic Industries Co., Ltd.) using a jet mill and a wind classifier (DS classifier;
5. Nippon Pneumatic Industrial Co., Ltd.)
5 μm black colored particles (K-1) were obtained.

Stir well with 600 parts of water 1200 parts of Pigment Yellow 17 water-containing cake (50% solid content) with a flasher. Here, 1200 parts of polyester resin A was added, and kneaded at 150 ° C. for 30 minutes.
After adding 1000 parts of xylene and kneading for 1 hour, removing water and xylene, rolling, cooling, pulverizing with a pulperizer, and passing twice with three rolls, a master batch pigment was obtained.

100 parts of polyester resin A 5 parts of master batch 5 parts of charge control resin A 5 parts The above materials were mixed by a mixer, then melt-kneaded by a two-roll mill, and the kneaded product was rolled and cooled. Thereafter, pulverization and classification were performed in the same manner as in the production example of the black colored particles, and the weight average diameter was 6.
6 μm yellow colored particles (Y-1) were obtained.

Water 600 parts Pigment Red 57 water-containing cake (solid content 50%) 1200 parts The above is thoroughly stirred with a flasher. To this, 1200 parts of polyester resin A was added, kneaded at 150 ° C. for 30 minutes, 1000 parts of xylene was added, kneading was continued for 1 hour, water and xylene were removed, roll-cooled, and pulverized with a pulperizer.
Further, the mixture was passed twice with a three-roll mill to obtain a master batch pigment.

Polyester resin A 100 parts Master batch 5 parts Charge control resin A 5 parts The above materials were mixed by a mixer, melt-kneaded by a two-roll mill, and the kneaded product was rolled and cooled. Thereafter, pulverization and classification were performed in the same manner as in the production example of the black colored particles, and the weight average diameter was 6.8.
μm magenta colored particles (M-1) were obtained.

Mix well 600 parts of water 1200 parts of Pigment Blue 15: 3 water-containing cake (50% solids) with a flasher. Here, 1200 parts of polyester resin A was added, and kneaded at 150 ° C. for 30 minutes.
After adding 1000 parts of xylene and kneading for further 1 hour, removing water and xylene, rolling and cooling, pulverizing with a pulperizer, and passing twice with a three-roll mill, a master batch pigment was obtained.

100 parts of polyester resin A 3 parts of the above master batch 3 parts of charge control resin A 5 parts The above materials were mixed by a mixer, then melt-kneaded by a two-roll mill, and the kneaded product was rolled and cooled. Thereafter, pulverization and classification were performed in the same manner as in the production example of the black colored particles, and the weight average diameter was 6.
9 μm of cyan colored particles (C-1) were obtained. For each color, the polyester resin A is replaced with a polyol resin A.
In the same manner except for the above, black colored particles (K-2, weight average diameter 6.7 μm), yellow colored particles (Y-2, weight average diameter 6.7 μm), and magenta colored particles (M-2, weight Average diameter 6.6 μm) and cyan colored particles (C-2, weight average diameter 6.6 μm) were obtained.

(Mixing with External Additive and Evaluation of Obtained Toner) 100 parts by weight of the obtained four colored particles and the following external additives were used as hydrophobic silica (I) and hydrophobic silica ( III) and hydrophobic titanium oxide (II) (Tables 1 to 3) in Table 4.
The resulting mixture was mixed with a Henschel mixer at the amount indicated, and passed through a mesh having an opening of 38 μm to remove coarse particles and aggregates, thereby obtaining an electrophotographic toner.

Examples of additives

[Table 1]

[0089]

[Table 2]

[0090]

[Table 3]

Table 4 shows the evaluation results of the combinations and the obtained toners with various image evaluation machines.

[0092]

[Table 4]

When an image is evaluated with a two-component developer, a ferrite carrier coated with a silicone resin at an average thickness of 0.3 μm and having an average particle size of 50 μm is used. Was uniformly mixed and charged using a turbuler mixer of a type in which the container was rolled and stirred to prepare a developer.

(Toner Evaluation Machine) The obtained toner was prepared by applying a one-component developer to a full-color laser printer, Ipsio Color 5000 (manufactured by Ricoh Company, with an OPC belt, an intermediate transfer belt, and a zinc stearate micro-coating mechanism.
1. No zinc stearate coating mechanism, evaluation machine A-2) remodeled machine, Epsiocolor 2100 (manufactured by Ricoh Company, OPC belt, intermediate transfer drum, zinc stearate trace coating mechanism set, evaluation machine B) remodeled machine, or figure Test machine (OPC drum, intermediate transfer drum, evaluation machine C with zinc stearate micro-coating mechanism C) modified machine shown in No. 1 and full color laser copying machine Imagio Color 28 for two-component developer
00 (manufactured by Ricoh Company, intermediate transfer drum, intermediate transfer belt,
The evaluation was performed by an evaluation machine D) with a mars coating mechanism. The developing units of the evaluation machines A, B, and C are equipped with a developing sleeve made of an elastic body and a non-magnetic one-component developing unit made of a stainless steel blade having a regulated thickness. In addition, all of the four types of evaluation machines are of the reversal development type in which the polarity of the electrostatic latent image on the photoconductor and the polarity of the non-magnetic one-component developer are the same.

(Evaluation items) All items were initial and 5%
After running the image chart of the image area continuously up to 10,000 sheets, the following evaluation was performed.

1) Transfer Chile The printed image was observed with a magnifier of 30 times for the state of dust at the image edge.は is a sharp image with almost no dust, △ is slightly visible but lacks sharpness, and × is not a sharply sharp and clear image, and terrible is the background stain.

2) Transfer Misalignment The printed image was visually observed, and the state of transfer omission (blurring) of the solid image portion was confirmed with a 30 × loupe. ○ is a good image without unevenness, △ is slightly observed but cannot be visually confirmed, and × is visually confirmed, and uneven color and the like are generated.

3) Background Stain The white paper image was stopped during the development, the developer on the photoreceptor after the development was transferred to the tape, and the difference from the image density of the untransferred tape was measured using a 938 spectrodensitometer (X-Rite). Measured by the company).

4) Others Other images and development parts are checked for the following. Of these, those that were particularly problematic were noted.

Thin layer forming property: The thin layer property of the toner on the developing sleeve was visually observed. Many white streaks occur,
Some of the images appeared as streaks. Toner replenishability: A solid image was formed, and the follow-up of density was confirmed. m / a, TC: Among the developing units, the toner amount per fixed area on the sleeve was confirmed for the one-component developing system, and the toner concentration was confirmed for the two-component developing system. The terrible thing had a large change amount compared to the initial stage, and the toner supply amount increased, resulting in background contamination.

5) Measurement of Physical Properties 6-1) [Particle Size] The particle size of the toner was measured using a particle size analyzer “Coulter Counter TAII” manufactured by Coulter Electronics Co., Ltd., with an aperture diameter of 100 μm. The weight average particle size was determined by the above particle size analyzer.

6-2) [Charge Amount] In the case of a two-component developer, 6 g of the developer is weighed, charged into a sealable metal cylinder, and blown to determine the charge amount. The toner concentration is adjusted to 4.5 to 5.5 wt%. In the case of one-component toner, the toner is transported on a developing roller (sleeve),
It measured by the suction tribo-measurement method under each environment. Note that the temperature and humidity were set at 23 ° C. and 50%. Table 5 summarizes Examples 1 to 10 and Comparative Examples 1 to 5 implemented as described above.

[0103]

[Table 5]

[0104]

As described above, according to the present invention, the intermediate transfer method and the contact (2)
Next) In the generation of a full-color image using the transfer method, at least three types of external additives specified for the four color toners of yellow, cyan, magenta, and black are used, and the added amount and the toner charge amount are developed. By optimizing in order, it is possible to supply an image with high reproducibility without transfer dust, transfer omission (transfer blur), and background fogging, and it is possible to supply a stable image over time.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating an example of a color image recording method that can be used in the present invention.

[Explanation of symbols]

 1a to 1d: developing devices for each color 2: photoreceptor 3: intermediate transfer member 4: transfer bias roller 5: fixing device 6: transfer material

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification FI FI Theme Court ゛ (Reference) G03G 15/16 103 G03G 9/08 331 361 (72) Inventor Shinichiro Yagi 1-3-3 Nakamagome, Ota-ku, Tokyo No. 6 Inside Ricoh Co., Ltd. (72) Inventor Toshiki Minatani 1-3-6 Nakamagome, Ota-ku, Tokyo F-term inside Ricoh Co., Ltd. 2H005 AA01 AA08 AA21 CA08 CA15 CB07 CB13 EA01 EA05 EA10 2H030 BB02 BB24 BB42 BB53 BB63 2H200 FA02 GA24 GA34 GA46 GA47 GA50 GB02 GB03 GB12 GB13 HA02 HB12 HB22 JA02 JA08 JA29 JC04 JC12 LB01 LB39 PA12 PA14 PA26

Claims (26)

[Claims] 1. An image carrier having four color developing units of yellow, cyan, magenta, and black, each of which forms an electrostatic latent image on an image carrier, and develops the electrostatic latent image with each toner. After performing the step of primary transferring the toner image on the intermediate transfer member, the toner image on the intermediate transfer member is secondarily transferred to the transfer member at a time, and when the toner on the transfer member is fixed, a full-color image is formed. In a full-color image forming method in which reproduction is performed with three colors of yellow, cyan, and magenta, and only black is used as a single color, a. The color toner is a toner containing at least a binder resin and a coloring material, and further containing at least the following three types of external additives, and a silica having a primary particle diameter of 0.01 to 0.03 μm and subjected to hydrophobic treatment. Primary particle size 0.01 to 0.03 μm and specific surface area 60 to
140 m ² / g hydrophobized titanium oxide Specific surface area 30 to 150 m ² / g, bulk density 100 to 25
0 g / l hydrophobized silica b. ) Assuming that the toner in the earlier development order of cyan and magenta is A and the toner in the later development order is B, the added amount of the external additives is A> B, c. ) At this time, the absolute value of the toner charge amount | Q _A / m |
| Q _B / m | is | Q _A / m |> | Q _B / m | d. 2.) A full-color image forming method, wherein the secondary transfer is a method of transferring a toner image to a transfer member by bringing a transfer device to which a transfer bias is applied into contact with the transfer device at 3 g / cm or more. 2. An image bearing member having four color developing units of yellow, cyan, magenta, and black, each of which forms an electrostatic latent image on an image bearing member and develops the electrostatic latent image with each toner. Full-color image forming method in which after the step of primary transferring the upper toner image to the intermediate transfer member is performed, the toner image on the intermediate transfer member is collectively secondary-transferred to the transfer member, and the toner on the transfer member is fixed. In a. The color toner is a toner containing at least a binder resin and a coloring material, and further containing at least the following three types of external additives, and a silica having a primary particle diameter of 0.01 to 0.03 μm and subjected to hydrophobic treatment. Primary particle size 0.01 to 0.03 μm and specific surface area 60 to
140 m ² / g hydrophobized titanium oxide Specific surface area 30 to 150 m ² / g, bulk density 100 to 25
0 g / l hydrophobized silica b. ) When the toner having the earliest development order among cyan, magenta and black is A, the toner having the second development order is B, and the toner having the latest development order is C, the addition amount of the external additives is A> B > C, c. ) At this time, the absolute value of the toner charge amount | Q _A / m |
_{| Q B / m |, |} Q C / m | is _{| Q A / m |> |} Q B / m |
> | Q _C / m | d. 2.) A full-color image forming method, wherein the secondary transfer is a method of transferring a toner image to a transfer member by bringing a transfer device to which a transfer bias is applied into contact with the transfer device at 3 g / cm or more. 3. An image carrier having developing units of four colors of yellow, cyan, magenta, and black, each of which forms an electrostatic latent image on an image carrier and develops the electrostatic latent image with each toner. Full-color image forming method in which after the step of primary transferring the upper toner image to the intermediate transfer member is performed, the toner image on the intermediate transfer member is collectively secondary-transferred to the transfer member, and the toner on the transfer member is fixed. In a. The color toner is a toner containing at least a binder resin and a coloring material, and further containing at least the following three types of external additives, and a silica having a primary particle diameter of 0.01 to 0.03 μm and subjected to hydrophobic treatment. Primary particle size 0.01 to 0.03 μm and specific surface area 60 to
140 m ² / g hydrophobized titanium oxide Specific surface area 30 to 150 m ² / g, bulk density 100 to 25
0 g / l hydrophobized silica b. When the toner having the earliest development order among yellow, cyan, magenta, and black is A, the second toner is B, the third toner is C, and the toner having the latest development order is D, The addition amount of which is A>B>C> D, c. ) At this time, the absolute value of the toner charge amount | Q _A / m |
| Q _B / m |, | Q _C / m |, | Q _D / m | is | Q _A / m |
_{> | Q B / m |>} | Q C / m |> | Q D / m | d. 2.) A full-color image forming method, wherein the secondary transfer is a method of transferring a toner image to a transfer member by bringing a transfer device to which a transfer bias is applied into contact with the transfer device at 3 g / cm or more. 4. The full-color image forming method according to claim 1, wherein said developing unit is a non-magnetic one-component developing system. 5. The full-color image forming method according to claim 1, wherein the intermediate transfer member is an intermediate transfer belt. 6. The full-color image forming method according to claim 1, wherein the image carrier is a photoreceptor belt. 7. The full-color image forming method according to claim 1, wherein a small amount of zinc stearate is applied to the intermediate transfer member. 8. The full-color image forming method according to claim 1, wherein the binder resin is a polyester resin and / or a polyol resin. 9. An image carrier having developing units of four colors of yellow, cyan, magenta, and black, each of which forms an electrostatic latent image on an image carrier and develops the electrostatic latent image with each toner. After the step of primary transferring the toner image on the intermediate transfer member to the intermediate transfer member, the toner image on the intermediate transfer member is secondarily transferred to the transfer member at a time, and the toner on the transfer member is fixed. In the full-color image forming method, the transfer is performed by transferring a toner image to a transfer member by bringing a transfer device to which a transfer bias is applied into contact with the transfer device at 3 g / cm or more. b. c. Color toner for developing electrostatic images that satisfies the following conditions. a. The color toner is a toner containing at least a binder resin and a coloring material, and further containing at least the following three types of external additives, and a silica having a primary particle diameter of 0.01 to 0.03 μm and subjected to hydrophobic treatment. Primary particle size 0.01 to 0.03 μm and specific surface area 60 to
140 m ² / g hydrophobized titanium oxide Specific surface area 30 to 150 m ² / g, bulk density 100 to 25
0 g / l hydrophobized silica b. ) Assuming that the toner in the earlier development order of cyan and magenta is A and the toner in the later development order is B, the added amount of the external additives is A> B, c. ) At this time, the absolute value of the toner charge amount | Q _A / m |
| Q _B / m | a _{| Q A / m |> |} Q B / m | 10. The color of yellow, cyan, magenta, and black
A step of forming an electrostatic latent image on the image carrier for each of the color developing units, developing the electrostatic latent image with each toner, and primarily transferring the toner image on the image carrier to the intermediate transfer member. After the transfer, the toner image on the intermediate transfer member is collectively secondary-transferred to a transfer member, the toner on the transfer member is fixed, and the secondary transfer is performed by a transfer device to which a transfer bias is applied at 3 g / cm.
The image forming method is characterized in that the method is such that the toner image is transferred to the transfer member by abutting as described above.
b. c. Color toner for developing electrostatic images that satisfies the following conditions. a. The color toner is a toner containing at least a binder resin and a coloring material, and further containing at least the following three types of external additives, and a silica having a primary particle diameter of 0.01 to 0.03 μm and subjected to hydrophobic treatment. Primary particle size 0.01 to 0.03 μm and specific surface area 60 to
140 m ² / g hydrophobized titanium oxide Specific surface area 30 to 150 m ² / g, bulk density 100 to 25
0 g / l hydrophobized silica b. ) When the toner having the earliest development order among cyan, magenta and black is A, the toner having the second development order is B, and the toner having the latest development order is C, the addition amount of the external additives is A> B > C, c. ) At this time, the absolute value of the toner charge amount | Q _A / m |
_{| Q B / m |, |} Q C / m | is _{| Q A / m |> |} Q B / m |
> | Q _C / m | 11. Yellow, cyan, magenta and black 4
A step of forming an electrostatic latent image on the image carrier for each of the color developing units, developing the electrostatic latent image with each toner, and primarily transferring the toner image on the image carrier to the intermediate transfer member. After the transfer, the toner image on the intermediate transfer member is collectively secondary-transferred to a transfer member, the toner on the transfer member is fixed, and the secondary transfer is performed by a transfer device to which a transfer bias is applied at 3 g / cm.
The image forming system is characterized in that it is a system in which the toner image is transferred to a transfer member by abutting as described above.
b. c. Color toner for developing electrostatic images that satisfies the following conditions. a. The color toner is a toner containing at least a binder resin and a coloring material, and further containing at least the following three types of external additives, and a silica having a primary particle diameter of 0.01 to 0.03 μm and subjected to hydrophobic treatment. Primary particle size 0.01 to 0.03 μm and specific surface area 60 to
140 m ² / g hydrophobized titanium oxide Specific surface area 30 to 150 m ² / g, bulk density 100 to 25
0 g / l hydrophobized silica b. When the toner having the earliest development order among yellow, cyan, magenta, and black is A, the second toner is B, the third toner is C, and the toner having the latest development order is D, The addition amount of which is A>B>C> D, c. ) At this time, the absolute value of the toner charge amount | Q _A / m |
| Q _B / m |, | Q _C / m |, | Q _D / m | is | Q _A / m |
_{> | Q B / m |>} | Q C / m |> | Q D / m | 12. The color toner for developing an electrostatic image according to claim 9, wherein the developing unit is of a non-magnetic one-component developing type. 13. The color toner for developing an electrostatic image according to claim 9, wherein the binder resin is a polyester resin and / or a polyol resin. 14. Yellow, cyan, magenta and black 4
A step of forming an electrostatic latent image on the image carrier for each of the color developing units, developing the electrostatic latent image with each toner, and primarily transferring the toner image on the image carrier to the intermediate transfer member. After that, the toner image on the intermediate transfer body is secondarily transferred collectively to a transfer member, and when the toner on the transfer member is fixed, full-color reproduction is performed with three colors of yellow, cyan, and magenta superimposed. In a full-color image forming apparatus using only black as a single color, a. The color toner is a toner containing at least a binder resin and a coloring material, and further containing at least the following three types of external additives, and a silica having a primary particle diameter of 0.01 to 0.03 μm and subjected to hydrophobic treatment. Primary particle size 0.01 to 0.03 μm and specific surface area 60 to
140 m ² / g hydrophobized titanium oxide Specific surface area 30 to 150 m ² / g, bulk density 100 to 25
0 g / l hydrophobized silica b. ) Assuming that the toner in the earlier development order of cyan and magenta is A and the toner in the later development order is B, the added amount of the external additives is A> B, c. ) At this time, the absolute value of the toner charge amount | Q _A / m |
| Q _B / m | is | Q _A / m |> | Q _B / m | d. The image forming apparatus is characterized in that the secondary transfer is a method of transferring a toner image to a transfer member by bringing a transfer device to which a transfer bias is applied into contact with the transfer device at 3 g / cm or more. 15. The four colors of yellow, cyan, magenta, and black
A step of forming an electrostatic latent image on the image carrier for each of the color developing units, developing the electrostatic latent image with each toner, and primarily transferring the toner image on the image carrier to the intermediate transfer member. After that, the toner image on the intermediate transfer body is secondarily transferred collectively to a transfer member, and the toner on the transfer member is fixed in the full-color image forming apparatus. The color toner is a toner containing at least a binder resin and a coloring material, and further containing at least the following three types of external additives, and a silica having a primary particle diameter of 0.01 to 0.03 μm and subjected to hydrophobic treatment. Primary particle size 0.01 to 0.03 μm and specific surface area 60 to
140 m ² / g hydrophobized titanium oxide Specific surface area 30 to 150 m ² / g, bulk density 100 to 25
0 g / l hydrophobized silica b. ) When the toner having the earliest development order among cyan, magenta and black is A, the toner having the second development order is B, and the toner having the latest development order is C, the addition amount of the external additives is A> B > C, c. ) At this time, the absolute value of the toner charge amount | Q _A / m |
_{| Q B / m |, |} Q C / m | is _{| Q A / m |> |} Q B / m |
> | Q _C / m | d. The image forming apparatus is characterized in that the secondary transfer is a method of transferring a toner image to a transfer member by bringing a transfer device to which a transfer bias is applied into contact with the transfer device at 3 g / cm or more. 16. The four colors of yellow, cyan, magenta, and black
A step of forming an electrostatic latent image on the image carrier for each of the color developing units, developing the electrostatic latent image with each toner, and primarily transferring the toner image on the image carrier to the intermediate transfer member. After that, the toner image on the intermediate transfer body is secondarily transferred collectively to a transfer member, and the toner on the transfer member is fixed in the full-color image forming apparatus. The color toner is a toner containing at least a binder resin and a coloring material, and further containing at least the following three types of external additives, and a silica having a primary particle diameter of 0.01 to 0.03 μm and subjected to hydrophobic treatment. Primary particle size 0.01 to 0.03 μm and specific surface area 60 to
140 m ² / g hydrophobized titanium oxide Specific surface area 30 to 150 m ² / g, bulk density 100 to 25
0 g / l hydrophobized silica b. When the toner having the earliest development order among yellow, cyan, magenta, and black is A, the second toner is B, the third toner is C, and the toner having the latest development order is D, The addition amount of which is A>B>C> D, c. ) At this time, the absolute value of the toner charge amount | Q _A / m |
| Q _B / m |, | Q _C / m |, | Q _D / m | is | Q _A / m |
_{> | Q B / m |>} | Q C / m |> | Q D / m | d. The image forming apparatus is characterized in that the secondary transfer is a method of transferring a toner image to a transfer member by bringing a transfer device to which a transfer bias is applied into contact with the transfer device at 3 g / cm or more. 17. The image forming apparatus according to claim 14, wherein said developing unit is of a non-magnetic one-component developing type. 18. An image forming apparatus according to claim 14, wherein said intermediate transfer member is an intermediate transfer belt. 19. The image forming apparatus according to claim 14, wherein the image carrier is a photoreceptor belt. 20. The image forming apparatus according to claim 14, wherein a small amount of zinc stearate is applied to the intermediate transfer member. 21. The image forming apparatus according to claim 14, wherein the binder resin is a polyester resin and / or a polyol resin. 22. Yellow, cyan, magenta, and black 4
A step of forming an electrostatic latent image on the image carrier for each of the color developing units, developing the electrostatic latent image with each toner, and primarily transferring the toner image on the image carrier to the intermediate transfer member. After the transfer, the toner image on the intermediate transfer member is collectively secondary-transferred to a transfer member, the toner on the transfer member is fixed, and the secondary transfer is performed by a transfer device to which a transfer bias is applied at 3 g / cm.
In the full-color image forming apparatus, a method of transferring a toner image to a transfer member by abutting as described above. b. c. Color toner for developing electrostatic images that satisfies the following conditions. a. The color toner is a toner containing at least a binder resin and a coloring material, and further containing at least the following three types of external additives, and a silica having a primary particle diameter of 0.01 to 0.03 μm and subjected to hydrophobic treatment. Primary particle size 0.01 to 0.03 μm and specific surface area 60 to
140 m ² / g hydrophobized titanium oxide Specific surface area 30 to 150 m ² / g, bulk density 100 to 25
0 g / l hydrophobized silica b. ) Assuming that the toner in the earlier development order of cyan and magenta is A and the toner in the later development order is B, the added amount of the external additives is A> B, c. ) At this time, the absolute value of the toner charge amount | Q _A / m |
| Q _B / m | a _{| Q A / m |> |} Q B / m | 23. Yellow, cyan, magenta and black 4
A step of forming an electrostatic latent image on the image carrier for each of the color developing units, developing the electrostatic latent image with each toner, and primarily transferring the toner image on the image carrier to the intermediate transfer member. After the transfer, the toner image on the intermediate transfer member is collectively secondary-transferred to a transfer member, the toner on the transfer member is fixed, and the secondary transfer is performed by a transfer device to which a transfer bias is applied at 3 g / cm.
The full color image forming apparatus is characterized in that the toner image is transferred to a transfer member by abutting as described above. b. c. Color toner for developing electrostatic images that satisfies the following conditions. a. The color toner is a toner containing at least a binder resin and a coloring material, and further containing at least the following three types of external additives, and a silica having a primary particle diameter of 0.01 to 0.03 μm and subjected to hydrophobic treatment. Primary particle size 0.01 to 0.03 μm and specific surface area 60 to
140 m ² / g hydrophobized titanium oxide Specific surface area 30 to 150 m ² / g, bulk density 100 to 25
0 g / l hydrophobized silica b. ) When the toner having the earliest development order among cyan, magenta and black is A, the toner having the second development order is B, and the toner having the latest development order is C, the addition amount of the external additives is A> B > C, c. ) At this time, the absolute value of the toner charge amount | Q _A / m |
_{| Q B / m |, |} Q C / m | is _{| Q A / m |> |} Q B / m |
> | Q _C / m | 24. Yellow, cyan, magenta and black 4
A step of forming an electrostatic latent image on the image carrier for each of the color developing units, developing the electrostatic latent image with each toner, and primarily transferring the toner image on the image carrier to the intermediate transfer member. After the transfer, the toner image on the intermediate transfer member is collectively secondary-transferred to a transfer member, the toner on the transfer member is fixed, and the secondary transfer is performed by a transfer device to which a transfer bias is applied at 3 g / cm.
In the image forming apparatus, a method of transferring a toner image to a transfer member by abutting as described above is used.
b. c. Color toner for developing electrostatic images that satisfies the following conditions. a. The color toner is a toner containing at least a binder resin and a coloring material, and further containing at least the following three types of external additives, and a silica having a primary particle diameter of 0.01 to 0.03 μm and subjected to hydrophobic treatment. Primary particle size 0.01 to 0.03 μm and specific surface area 60 to
140 m ² / g hydrophobized titanium oxide Specific surface area 30 to 150 m ² / g, bulk density 100 to 25
0 g / l hydrophobized silica b. When the toner having the earliest development order among yellow, cyan, magenta, and black is A, the second toner is B, the third toner is C, and the toner having the latest development order is D, The addition amount of which is A>B>C> D, c. ) At this time, the absolute value of the toner charge amount | Q _A / m |
| Q _B / m |, | Q _C / m |, | Q _D / m | is | Q _A / m |
_{> | Q B / m |>} | Q C / m |> | Q D / m | 25. The color toner for developing an electrostatic image according to claim 22, wherein the developing unit is a non-magnetic one-component developing system. 26. The color toner according to claim 22, wherein the binder resin is a polyester resin and / or a polyol resin.